1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a phase transition type valve that is melted by a heat source to open a blocked channel so that a fluid can flow through the channel, and a method of manufacturing the valve.
2. Description of the Related Art
In biochemical experiments such as blood tests, many processes are performed to obtain desired resultants, for example, components of blood having different specific gravities are phase-separated and properties and shape of the desired component are changed by injecting a reagent. If a series of processes are performed manually one by one, it takes a long time, and error generating components are likely to be introduced into the test blood whenever the blood is moved for performing another process. Therefore, a biochemical reaction chip 10 shown in FIG. 1 is generally used so that the series of processes can be performed at one place automatically and rapidly.
In the chip 10, a channel 13, through which a test liquid 1 and a reagent 2 can flow, is formed so that the test liquid 1 and the reagent 2 flow through the channel 13 at a desired time point to perform the processes. For example, a simple sequence in which the reagent is mixed with an upper layer of the test liquid 1 that is phase separated resulting in a resultant coming out through an outlet 12, can be performed as follows. That is, the test liquid 1 is injected through an inlet 11, and a motor 14 is driven to rotate the chip 10. Then, the test liquid 1 is phase-separated due to the centrifugal force. Since the test liquid 1 should not flow through the channel 13 before the phase-separation is finished, a phase transition type valve 15a blocks the channel 13, and then, the valve 15a is opened when the phase-separation is finished. The phase transition type valve 15a is obtained by hardening a hydrophobic material such as wax in a predetermined section of the channel 13, and thus, the wax is melted by the heat energy and the channel 13 is opened. Therefore, when the phase separation is finished and the desired component is collected in the upper layer, a laser is irradiated onto the corresponding valve 15a using a laser diode 16 to melt the valve 15a. Then, the channel 13 is opened, and the upper liquid in the test liquid 1 flows along the channel 13. In addition, the valve 15b blocking the reagent 2 is melted by the laser, and then, the test liquid 1 and the reagent 2 are mixed with each other to make the resultant which is discharged through the outlet 12. The above series of processes are automatically controlled by a controller (not shown), and thus, all the user has to do is just input the test liquid 1 into the inlet 11, and then, start operation of the apparatus to obtain the resultant through the automatic processes.
In order to perform the automatic processes sufficiently, the valves 15a and 15b should be opened precisely at the desired point in time, and thus, the valves 15a and 15b should be hardened exactly at the set positions where the valves 15a and 15b are fabricated. That is, the opening of the valves 15a and 15b is performed by melting the valves 15a and 15b using the laser beam emitted from the laser diode 16, and thus, a focusing region of the laser beam emitted from the laser diode 16 is set to be slightly larger than the sizes of the valves 15a and 15b, and the laser is automatically controlled to be irradiated precisely at predetermined regions. Therefore, if the valves 15a and 15b are hardened out of the predetermined regions, or are hardened larger than a predetermined size of the valves 15a and 15b, the channel 13 is not completely opened even when the laser is irradiated.
The above problem occurs frequently when the valves 15a and 15b are fabricated by injecting the wax onto the corresponding portion of the channel 13. For example, as shown in FIG. 2A, even if the wax 15 is injected through an injection hole 10a with the intention of forming the valve at a section L, the wax 15 may be inclined to one side as shown in FIG. 2B (FIG. 2C is a photograph showing the situation of FIG. 2B), or may be spread wider than is expected as shown in FIG. 2D. In order to solve the above problem, a process for adjusting the hardened location of the wax 15 after injecting the wax 15 should be performed, and the processes of fabricating the valve becomes complex.